Impairment Charges and Reserves - Impairment Charges on Assets or Investments (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Impairment Charges And Impairment Of Joint Venture Investments [Abstract]
Assets marketed for sale	$ 600	$ 0
Assets included in the spin-off of RVI	0	30,400
Reserve of preferred equity interests	1,099	3,961
Total impairment charges	$ 1,700	$ 34,400

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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Name:	us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration